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问题 选择题

一列简谐波在均匀介质中传播．甲图表示t=0时刻的波形图，乙图表示甲图中b质点从t=0开始计时的振动图象，则（　　）

A．该波沿x轴负方向传播

B．质点振动的频率是4HZ

C．该波传播的速度是8m/s

D．a质点和c质点在振动过程中任意时刻的位移都相同

答案

A、由乙图知，t=0时刻，质点b向上运动，在甲图上，由波形的平移可知，该波沿x轴正方向传播．故A错误．

B、由乙图知，质点的振动周期为T=0.5s，则频率为f=

1
T
=2Hz，故B错误．

C、由甲图知，波长λ=4m，则波速为v=

λ
T
=
4
0.5
m/s=8m/s，故C正确．

D、a质点和c质点的平衡位置相距半个波长，振动情况总是相反，所以在振动过程中任意时刻的位移都相反，故D错误．

故选C

选择题

下列各组物质的溶液，不能发生复分解反应的一组是[ ]

A．HCl跟NaOH

B．Na2CO3跟H2SO4

C．KNO3跟NaCl

D．NaOH跟CuSO4
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单项选择题

D

People often say that the Englishman’s home is his castle. They mean that the home is very important and personal to him. Most people in Britain live in houses rather than flats, and many people own their homes. This means that they can make them individual(个体的); they can paint them, and change them in any way they like. Most houses have a garden, even if it is a very small one, and the garden is usually loved. The house and the garden are the private(私人的) space of the individual.

People usually like to mark their space. Are you sitting now in your home or on a train Have you marked the space around yourself as yours If you are on the train you may put your coat or small bag on the seat beside you. If you share a flat you may have one corner or chair which is your own.

Once I was travelling on a train to London. I was in a section for four people and there was a table between us. The man on the opposite side to me had his briefcase on the table. There was no space on my side of the table at all. I was angry. Maybe he thought that he owned the whole table. I had read a book about nonverbal communication, so I took various papers out of my bag and put them on his briefcase! When I did this he stiffened and his eyes nearly popped(瞪出)out of his head. I had invaded(侵犯)his space! A few minutes later I took my papers off his case in order to read them. He immediately moved his case to his side of the table. Of course, it is possible that he just wanted to be helpful to me!

If you are visiting another country you may feel that you don’t have any private space. Hotel rooms look much the same in every country in the world. All day long, you share public spaces with other people. You see the local people in their private spaces and you feel lonely and "outside". Local people can create their private spaces by talking about things you don’t know about. And you even feel that they like you to be outside them so that they will enjoy being inside even more! This is one of the difficulties of being a traveller! But if you understand it then it helps you. Haven’t you enjoyed being part of a group and" owning" a bit of space

In Paragraph 4, the pronoun "them" refers to (所指) （）.

A．public spaces

B．private spaces

C．local people

D．other countries
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